Identification of Abnormal Neuromagnetic Signatures in the Motor Cortex of Adolescent Migraine

(Headache 2010;50:1005‐1016) Objective.— To investigate the functional abnormalities of the motor cortices in children with migraine using magnetoencephalography (MEG) and a finger‐tapping task. Background.— Cortical hyperexcitability has been reported in adults with migraine using MEG. Many children with migraine report difficulty with motor functioning. There is no report on motor‐evoked magnetic activation in children with migraine using MEG and the latest signal processing methods. Methods.— Ten children with migraine (all female, 9 right‐handed and 1 left‐handed, aged 13‐17 years) and 10 age‐ and gender‐matched healthy children were studied with a 275‐channel MEG system. After hearing a unilateral, randomly presented sound cue (500 Hz, 30 milliseconds square tone), each subject immediately performed a brisk index finger tapping with either the right or the left index finger. The auditory stimuli consisted of 200 trials of square tone, 100 trials per ear, randomly distributed. The latency and amplitude of neuromagnetic responses were analyzed with averaged waveforms. Neuromagnetic sources were estimated using synthetic aperture magnetometry (SAM). SAM images were normalized for each participant for group comparison. Results.— In comparison with healthy children, children with migraine had prolonged latency of motor‐evoked magnetic response in the right hemispheres during left finger movement (62.33 ± 34.55 milliseconds vs 34.9 ± 17.29 milliseconds, P < .05). In addition, children with migraine had stronger activation in the motor cortex during right finger movement (8097.46 ± 5168.99 vs 4697.54 ± 3194.74, P < .05). Conclusions.— The results suggest that there are neurophysiological changes in the motor cortices of children with migraine that can be measured with neuromagnetic imaging techniques. The findings expand the ability to study the cerebral mechanisms of migraine using MEG and may facilitate the development of new therapeutic strategies in migraine treatment via alterations in cortical excitability.